SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9b5068c4e246f0a5f532bc551bce17be80d43719a410ca2095debededd538ac' 
  AND token = 'F2GjNTpMvsP4wJ8mL7VbKZ+yCQdHLhq4al+EDeVhjL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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