SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '804758a7bf52b36ea02932de2f7f0f374b7a63916397084d65ec3487d4b5d876' 
  AND token = 'j+8nzs+Bx+ZHJKo5BLmvd8MQmRe2GJ3TSnTG++lfNAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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