SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8eea64647abe68a2eb6bbc2641758479a6888a10448d01fd2a523f149a675a' 
  AND token = 'gBrOGGleX0ndmQ5It5kdEZT/EfsdWHKmU3ROUtD5lPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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