SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a5c729241d2cebc83e7d41976010651845ccd709a47cf4a8f83e792fdd1b54e' 
  AND token = 'AgKyj/V9Lf6IY/01oCUv9roLkKfNPVSZZVDGGCuhy1M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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