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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '683a9c7642ca81767a09944c93ddfe7339d1c97b0850c7c18efb7d287da7dd47' 
  AND token = 'mJ4Zzw2ckgCHwqI2eEl+ssEg1/2CHk6UaoWsLQJJz0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}