SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e8b72e7d1a1061d98a5f51151329eeafdb3578f06c904bb3d83e2dcac5e7b25' 
  AND token = '+fioNUr2XgImAb2lbCmSgogf9ewXATO2cRPwHAwguRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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