SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fcae9066177b7034b181458cd17e62c3598b7e9513a2bd9ee052ce06816aa64' 
  AND token = 'ZbdrlKiSIHVv6AvuyuorCPbKpt9qqmvRdgi1gJ1zbw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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