SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fc8b92d1d7e7a0e33f61fe05a3778440fb8c25d80ccb7f51ea6082b79375d45' 
  AND token = '8dmCmTAuGhmvKULAlCYctKWhVmxS3N8mQ84cTFE9gME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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