SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b56b43b3b05e2d0c8e03769c7568824d1d77a1fca4ea9b65b80e3540324ba474' 
  AND token = 'mGsIPzcoCv/+Li3etwhMZgHfo9J1h9uZzbZ59YHoBY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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