SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd9bfff44cb7b165d98ae5557e5e8172ec0bdfa9f970642d5dbac2355cf94d85' 
  AND token = 'YgOmHU1lM+yIh7DqJnI0Sv/pBHCrMoG5RKZk/wNcjAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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