SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49cee79a21376d546146a41453fab96c54a41b9f8ac4faee97229299d813cc9d' 
  AND token = 'E7+TekUa7r+osbiQMp8PqMSc43VfBhEPrDXIwKdVLhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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