SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa0921ffe76153b38069ad36935b4aedc539a6a59bc79c83fc61a3f408e2a6f3' 
  AND token = 'aOxK1vITNx0wk/4yWCV0S4x2oSY34sRP0ueeW4swd/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00102

JSON explain

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