SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f351749465b88d005754c8d12e5c145047720a612c37f06c4f763f0411cbbdee' 
  AND token = 'naVajJFuhEwdQCsrAZUIZOQ/ATMR9dvwnUdlNX11WAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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