SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2efaab53f1557bbbb14a2f21975b3fc4e2c9b476223717dc9b0ac05335bdeaa5' 
  AND token = '1gvJyKguA7so62pmpmHuBpIJwWrid2Pv4jBiqcRqVI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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