SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5849549aab2f257b9b3a336a6a0c402548b4009921835807a6003fe683c89298' 
  AND token = '/Da4FBJ6RI4Y7ljO6sntavJUFrBAvY2vkAsE1pDpZnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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