SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1974ee8182113f7e0ac711d52f2c636ba8b4b7de9e0ea834ad6d6a823574fac1' 
  AND token = '93A0h6KMr3YcxVSAGw+F62tYUAkmtCgEfpefD3T73Ug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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