SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b7cf75be211ef968bed5ba7c08923dc505af48d638e24e8818ab69d1984b7b0' 
  AND token = '9hXMb/KSFuzthZz+Ttza8PDr5BWP3sqkGtQGrHtMq+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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