SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6890dc4d0652590a260fc9cca6a148b750e8093a531feb4a5b7eefdf7db4a1e1' 
  AND token = '4xjzHMwpS9ZX8BJz75/Pf5Wo/xkSLe+F53G2yVvOhQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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