SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e51fc910d16f31d9a3a2e1b29d5aa70ef447974773f730dd2f267a3038aee8f0' 
  AND token = 'uRPWFy4as0TMP57fDMKri5AJgxUIFDEiYrpbnWoQkzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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