SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b806df17e0f96e31ff272497e4808f27a0177a38baa9ea0b5f1b9b519d61de5f' 
  AND token = 'tJ9+Uzq7BzF+D7K7cLeepnprh/2qoB34cW+NmX4VOjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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