SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '61bc779735582b88a7b392769f3de15676074b861afd97604863d615f9c2f7f5' 
  AND token = 'xtLo5jEOc0w5HS3vq3oZ3KxBpr+rMVoRcjhtoalXsSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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