SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a686815e4e31ee053e61e9bd89ea8a0da527224aff284d0255b68e48cee67b5' 
  AND token = 'jZAs651c9h4mSYILKEALmTLwbYJwCMxXPByKnKoJQS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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