SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad283cdb9da20a618fcf7692af4bc5906db8f3843e5bbd08f739e0396e910b2e' 
  AND token = '5CzxPflPjgwsQjQqWBkcw0pF1RXqzMKxpUBE6bBNtXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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