SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82a465c23ee459911d990fbf001692cc9138ed2b12c4989f40d60287e7989895' 
  AND token = 'Id4txeUT3VS+ZuwGsIDjIQaRZ/PzCKUhWnPmlTnYSVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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