SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b255ae15413c0878dabe7b667ff2534752de6e296b78d8f6128e0b58bd32949' 
  AND token = 'rRfd/WLddb4D+GqSCbbJo2yisbeOcz2nePXmSxR3nDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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