SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6050ea654a31ce1f344e0179ea3c0503260273f66b0ea643f57315726f0e9c7c' 
  AND token = 'pPHFXkrWecBEpapOmwfFKVEdoASh+AHYwg+cWQKA5s4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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