SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a7574b4adbc4ed41d355577579bb82451ae5868d030f93d7b11641862928f4a' 
  AND token = '8R+HOWVnnWG8lJgJtw1q7RfuQv2vjcDDU+DYrSqDHg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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