SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec91294d97480a62580c327f054953d20076d89d3f925a30af33143e68cbee0b' 
  AND token = 'PIFVDy/P2ypszY9CkB5hIaYQpvXv3dogucfnGI03tBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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