SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '5a78f09e5b4c3f18791de5238b92105517ecc8aa8a39aa0f4018d561155a0862' 
  AND token = 'CY0/id3ujGY3faHBPLCY+bI572ppw42cdevxqKv/+TU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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