SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f621caf19e70bf7a1442521e4205c77c52007ae413cf755e8b3e00db6364307d' 
  AND token = 'eIY9lFQSwJzI4/eyIMCO2osoDS2ahleBHp5yHxPhEP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}