SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29bd51e82d1b2bec4f9f17e3298cbab3bbb6c3066881e3874707898c4bf7ce6d' 
  AND token = 'qDBqbGs3muPJKci3Ra/Quc/YwUEk6i+Rpxc1amE87gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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