SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dbd92d728aa3b57b8d01fede9645451b4e37288f6414ff3da0b19c80884d877' 
  AND token = 'yY59+mw1zhFkkw/WJZUeZLJi9cDGoaUoaWBCNXV3Ed4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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