SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3eb7316fa6fead7cd33857f1a2c5d328628ec07ea73fcd44d63c5aeb389edd9' 
  AND token = 'fZ+nafb+Ij21EYPrb70QmN+qpLCuxEmFVFwCpBtGHZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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