SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b50cacd0e8563cacb82d321be1d040b44418f87d225122b131772cb7a2d17e2a' 
  AND token = '/eLQSaY3op1vWNlcCngyQuR3DeSc1AGlUWZ6oaHQznE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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