SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8da9cbbe927dbee35d9263848e8af6c2d9513c56efa3566a28eab6e50e20d731' 
  AND token = 'jx7cOA+v/8171dwNyUM3RbuFkeBm9n5p+Rm5An4uPWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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