SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5577479d0bf6ac58966fd97d41f2d91c9935c5427febde7aec9496aedcf28c9' 
  AND token = 'xTGerhmm731C6ugRt/ThykfM+9LZSOTCr3yQPAW+n78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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