SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3609b2d4059d557797493d16095b7dabea0868d94019bf0874d903c902634737' 
  AND token = 'DnxkWptgR6zwJoGfU124iIKTIJ1WPgBEI8ArgMKH9iY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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