SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '9dd0d6175295961fd71938afda358d7a02294cb68672fc1d38d5cc477fcde825' 
  AND token = 'Kte4DKGKFy8pwedBE5sfmySt8BI/HYKzHStjzkPaAn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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