SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eff626e6c8a06eb60d57907f0c3ed1fd1c1d31405ef96f860c6436423bde6c89' 
  AND token = 'gmwkPcMTvl1Xm8heGoqCACU7gdCR7tJcoetIiqtXtJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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