SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '597c93b4980387a863f44d73292143d755d221343cba596b5f11a16186f9eec4' 
  AND token = 'xR9CvOBUmrchjkd15atJuTYX+Aj/MfxhWJDag8uENT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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