SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b6fb371ff1b89885549077929bb2e63f4120420c8edc07a721e97ada73ad42c' 
  AND token = 'L4NJWCEkGKE7N0i2iYVZz/3uPMjYjuCeqO2n9wnwclU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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