SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81a4c17261fbc868ebd70973606f3d9512887606727427991d933269e0e3945d' 
  AND token = 'nASkwfkeVZwgRBa0aKgpoBuLx9CUct5gnISB/v90Hp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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