SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c13ab8ec2b5d9931a84d1b6991fa45d2ceaf91d728b81a4dc748ed49bf2e75c' 
  AND token = '6zcCDsP+iGhsWsEkUV07ufxVKuv3ZR6PZgL5fUVk/oA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}