SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9bd38de18cfaa6d20c105218262e04811bafd85c80306eaffc6be3081a252f8' 
  AND token = 'OmRZ7zOVpASM57as/qKO+yInmZtIOvSMAiC0grBwW3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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